Concealed Genic Variability in Brazilian Populations of Drosophila Willistoni

Pavan, C.; Cordeiro, A. R.; Dobzhansky, N.; Dobzhansky, Th.; Malogolowkin, Chana; Spassky, B.; Wedel, Mathew

doi:10.1093/genetics/36.1.13

Cited by 54 publications

(20 citation statements)

References 11 publications

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“…The strains of D. willistoni were established as follows. Progenies of single wild females collected in two localities, Mirassol and Ribeirao Preto, in the state of Sao Paulo, Brazil, were outcrossed to laboratory stocks containing chromosome markers, as described by PAVAN et al ( 1951). After three generations of crosses two kinds of flies were obtained; some are homozygous for a second wild chromosome, and others are heterozygous for the same wild chromosome and a marker chromosome.…”

Section: Strainsmentioning

confidence: 99%

Competitive fitness in experimental populations of Drosophila willistoni

Mourao

Ayala

1971

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Experiments are reported in which genetically different strains of Drosophila willistoni compete with D. pseudoobscura. The competition was studied at three temperatures, 20°, 22°, and 25°C. The outcome of the competition depends on the genetic constitution of the competing species, but at 25° and 22°C D. willistoni flies are generally stronger competitors than D. pseudoobscura, while at 20°C D. pseudoobscura generally has a competitive advantage. There is a significant interaction between genotype and temperature; the strain RP3 is the weakest competitor of all D. willistoni strains at 22° and 25°C, but not at 20°C; the strain MIS is the best competitor at 20° and 22°C but not at 25°C.The performance of the four strains of D. willistoni was measured in two more ways. First we estimated their Darwinian fitness relative to other genotypes of the same species. Second, we measured the average population size of each strain in pure culture. There is no significant correlation between population size in pure culture and either competitive fitness or Darwinian fitness. There is, however, a strong positive correlation between Darwinian fitness and interspecific competitive fitness.It is pointed out that natural selection leads to an increase in the average Darwinian fitness of a population but not necessarily to an increase in its adaptedness to the environment. Yet the synthetic theory of evolution assumes that the genes and genotypes favored by natural selection are usually those which increase the adaptedness of their carriers to the environments where they live. The correlation between Darwinian fitness and adaptedness needs to be studied experimentally.

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Section: Strainsmentioning

confidence: 99%

Competitive fitness in experimental populations of Drosophila willistoni

Mourao

Ayala

1971

Genetica

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“…In D. willis toni, there are regions such as Rio Branco and Rio Negro which produce as much as 57.1 per cent sterility (Pavan et al, 1951). We have never recorded sterility this high for D. melanogaster in Colombia.…”

Section: Lethals and Semilethalsmentioning

confidence: 63%

“…The Altiplano population has more than 40 per cent sterile chromosomes, while the Duitama population carries only 15.6 per cent. Homozygous males from the Altiplano population have more than 30 per cent sterile chromosomes, while the cor- (Pavan et al, 1951) with relative uniformity in their genetic variants throughout Brazil. These authors interpret their results as indicative of the effect of adaptive polymorphism.…”

Section: Discussionmentioning

confidence: 99%

“…Since vegetation becomes dry and flies scarce, it was necessary to use some of the local fruits as bait. The mean temperature in Caracolisito is about 32° C. Chromosomes are considered lethals if the homozygotes show five per cent or less of the normal viability (Pavan et al, 1951). The normal viability is by definition that observed in the control experiments.…”

Section: Methodsmentioning

confidence: 99%

“…Genes for speed of development appear in different frequencies in different species. In D. willistoni (Pavan et al, 1951) and in D. pseudoobscura Pinon A 824 (Dobzhansky et al, 1942), most chromosomes produce normal development. There are certain populations of D. pseudoobscura which possess chromosomes for fast development (Pinon A 842), while others possess chromosomes for slow development (Pinon A 823) (see Dobzhansky et al, 1942).…”

Section: Lethals and Semilethalsmentioning

confidence: 99%

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